1. Field of the Invention
The present invention relates to a brake control apparatus for a bicycle, and more particularly to a control apparatus of the above type including a bracket, a brake lever pivoted to the bracket via a lever shaft and a lever spring for urging the brake lever to its home position relative to the bracket.
2. Description of the Prior Art
Such a conventional brake control apparatus is known from a Japanese patent laid open under No. 63-173781. This apparatus employs, as the lever spring, such urging means as a plate spring, a bar spring, a torsion coil spring, or a tension coil spring. Of these choices, the torsion coil spring or the tension coil spring are preferred since the plate spring or the bar spring has the disadvantage that its urging force varies significantly according to a pivotal amount of the brake lever.
However, when the torsion coil spring is employed, it becomes necessary to restrict displacement of the spring in a directional normal to a central axis thereof. To this end, the coil portion of the spring should have a smallest possible number of turns, and at the same time these turns should be wound as closely as possible to each other. As a result, an urging force of the thus constructed spring again varies significantly according to a pivotal amount of the brake lever. Moreover, when the spring is deformed with a brake lever operation, the turns of the coil portion of the spring radially displace, i.e. come into sliding contact with each other which contact produces unpleasant creaking noise to a cyclist.
On the other hand, the tension coil spring, as a lever spring, has the disadvantage of requiring large space in the bracket to permit free movements of the spring associated with brake lever operations. Hence, the tension coil spring is unsuitable for such brake control apparatuses which should be formed compact. If it is attempted to limit the amount of the spring movements, this will only result in generation of further creaking noise from sliding contact between the spring and a portion used for limiting the spring movement and will result also in disadvantageous complication of the construction around the spring.
In view of the above state of the art, the primary object of the present invention is to solve these problems of the prior art by providing an improved brake lever control apparatus for a bicycle. With this improved apparatus of the invention, the brake lever can be operated by approximately fixed, i.e. same manual force regardless of the amount of pivotal motion of the brake lever and the lever spring does not generate unpleasant creaking noise in the course of the breaking operation.